This invention relates to a low impedance safety guard for an air circulating fan with rotating fan blades.
It is well known that air circulating fans generally include an electrical fan motor having a protruding rotatable shaft for fixing a blade impeller thereon. The impeller typically includes several fan blades which draw air from the rear and impel it forwardly in a direction forward of the fan.
Many known older patented fan guards, cages, or shrouds characteristically are very open which effectively do not obstruct or impede the impelled air stream which is the objective of the air circulating fan, as shown in FIG. 1. However, guards of this style do not effectively prohibit objects from coming into contact with the rotating fan blades, such as human hands, fingers or toes. The following U.S. patents are illustrative of this open type of guard: U.S. Pat. Nos. 4,022,548; 3,347,452; 2,862,657; 2,728,519; 2,624,504; 2,617,583; 2,829,819; 2,259,853 and 2,017,431.
Because of the numbers of severed human appendages and other related types of injuries from the above identified style of fan safety guards, the Occupational Safety and Health Administration (OSHA) has required that fan shrouds or guards be more closed in their general overall structure, as shown in FIG. 2, to prevent hands, fingers and toes from getting into the path of the rotating blades. Fan safety guards which typically represent this closed style may be represented by the following U.S. Pat. Nos.: 4,657,485; 4,222,318; 3,963,382; 3,791,333; 3,787,142; and 3,262,638.
Problematically, the OSHA approved style of fan guard, although safe, unduly impedes, obstructs or baffles the air stream which defeats the objective of circulating the air by the use of a fan. Also, dust and dirt more readily collects on the highly restrictive style of guards.